Growth and accumulation of shikonin compounds of two kinds of cells in suspension culture of Arnebia euchroma / 中国中药杂志

Via studying the phenotype, growth curve and secondary metabolites of two kinds of suspension culture cell of Arnebia euchroma, the kinetics parameters of growth and accumulation of shikonin compounds in cell suspension culture of A. euchroma was obtained through simulating and modeling. This Study found that the red high-yielding one was a fine cell line for producing shikonin compounds, and the white low-yielding one may be a mutant. The first-order and second-order derivative of the fitting function were obtained by fitting the Logistic model of growth curve to get the growth rate and growth acceleration curve of the suspended cells. It is found that the best period to subculture was the 15th day cultured in fresh medium, and the best period of the induction process was the 13th-14th day. When compared the growth rate of the red line and the shikonin compounds accumulation curve, it is found that the rapid growth of the biomass of cells was not conducive to the synthesis and accumulation of shikonin compounds.

Metabolic engineering of terpenoids in plants / 生物工程学报

Terpenoids are present in all organisms but are especially abundant in plants, with more than 30,000 compounds. Not only do they play an important role in the life of plant, but also have high commercial values. However, the content of many important terpenoids in plant is very low. Therefore, how to improve the inefficient production of terpenoids is an urgent task. Metabolic engineering has been one of the most potential technologies to improve terpenoids production in recent years, following the study of metabolic pathway and regulation mechanism of terpenoids. Although there are some breakthroughs, metabolic engineering of terpenoids is still full of challenges because of the lack of knowledge on metabolic control of most terpenoids. Functional genomics approaches, including transcriptomics, proteomics and metabolomics, are potential tools for exploring of metabolic engineering. Integrating transcriptomics and metabolomics is an effective way to discover new genes involved in metabolic pathway. In this paper, the representative research outcomes about the metabolic engineering of terpenoids in plant were reviewed concisely and then the application of functional genomics approaches to study metabolic pathway and regulation mechanism of terpenoids and the strategies for metabolic engineering of terpenoids were discussed.

Advances in sesquiterpene synthases cyclases of Artemisia annua / 生物工程学报

Artemisinin,a new and a very potent antimalarial drug, is produced by the plant Artemisia annua L. with a very low yield ranging from 0.01% to 0.8% on a dry-weight basis. This makes artemisinin an expensive drug. Several studies reported chemical synthesis of the artemisinin, but none of them seems a viable economical alternative compared with the isolation of artemisinin from the plant. Hence, a higher artemisinin concentration in the plant is necessary for cheap antimalarial drug production. Many types of cyclic sesquiterpenes in Artemisia annua have been characterized to date, each derived from the common cyclic precursor FDP in a reaction catalyzed by a sesquiterpene synthase. Sesquiterpene synthases are widely regarded as the rate-determining regulatory enzymes in the pathways they participate, and a number of sesquiterpene synthases have been cloned from Artemisia annua up to now. This report is a brief review on the following sesquiterpene synthases: epi-cedrol synthase, amorpha-4,11-diene synthase, beta-caryophyllene synthase, (E)-beta-farnesene synthase, germacrene A synthase, as well as a new sesquiterpene synthase whose function remains largely unknown. The report is of help for a better understanding of metabolic engineering of Artemisia annua.

Advances in molecular regulation of artemisinin biosynthesis / 生物工程学报

Artemisinin, a new and a very potent antimalarial drug, is produced by the Chinese medicinal herb Artemisia annua L. It is a sesquiterpene lactone with an endoperoxide bridge and is active against chloroquine resistant forms of Plasmodium falciparum. The relatively low yield (0.01% - 0.6%) of artemisinin in A. annua is a serious limitation to the commercialization of the drug. Therefore, a through understanding of the biosynthetic pathway and the characterization of the involved enzymes are important for the biology production of artemisinin. This review is focused on the recent progress in the molecular regulation of artemisinin biosynthesis from the following aspects: the biosynthetic pathway of artemisinin, the key enzymes involved in artemisinin biosynthesis, and the molecular regulation of artemisinin biosynthesis. The biosynthetic pathway of artemisinin belongs to the isoprenoid metabolite pathway, the key enzymes involved in the biosynthesis of artemisinin include: 3-hydroxy-3-methylglutaryl-CoA reductase (HMGR), farnesyl diphosphate synthase (FDPS), and amorpha-4, 11-diene synthase, of which amorpha-4, 11-diene synthase catalyzes the cyclisation of the ubiquitous precursor farnesyl diphosphate to the highly specific olefinic sesquiter-pene skeletons and has been postulated as the regulatory step in the biosynthesis of artemisinin. Recently the gene encoding of the amorpha-4, 11-diene synthase has been cloned and the functional expressions have been studied by several research teams, therefore, the breakthroughs in production of artemisinin could hopefully be achieved by metabolic engineering of the plant, in particular, by over-expressing enzyme(s) catalyzing the rate limiting step(s) of artemisinin biosynthesis or by inhibiting the enzyme(s) of other pathway competing for its precursors. Besides, the effects of the heterogenesis isoprenoid pathway related genes on artemisinin biosynthesis of the transformed plants were also discussed.

Effect of factors on callus biomass and synthetic mass of hypericin in Hypericum perforatum / 中国中药杂志

<p><b>OBJECTIVE</b>To study the effect of several factors on the quantity of hypericin in H. perforatum callus.</p><p><b>METHOD</b>High efficiency liquid phase chromatography and plant tissue culture were applied.</p><p><b>RESULT AND CONCLUSION</b>When the ratio of nitro-nitrogen to amina-nitrogen is 3:1, the callus biomass is 1.6-fold and the synthetic mass of hypericin rises. 0.1-0.20 mg x L(-1) mannose improves the content of total hypericin. The addition of PVP or PVPP can promote improvement of the growth and biosynthesis of callus.</p>